Ladders

ABSTRACT

This invention relates to a ladder capable of being erected from a plurality of similar rungs and links, the ladder being capable of being folded in a zig-zag manner and also of being dismantled into a kit of component parts. The ladder comprises a plurality of rungs and side links which in the extended form of the ladder are adapted to maintain the spacing of the rungs and means between the rungs and the side links for inter-engagement.

United States Patent 1191 Lee Sept. 11, 1973 [54] LADDERS 2,592,006 4/1952 Burke 182/214 62 824 718 9 M 182164 [75] Inventor: William Waltham Alfred Lee, 1,0621 5 i; z g 182x64 Bognor Regls, England 2,998,863 9/1961 Larson 182/164 73 A W lth ms B nor R Lim'ted 1 sslgnee a a 0g egls) I Primary Examiner-Reinaldo P. Machado London, England Att0rneyStepno & Neilan [22] Filed: Jan. 26, 1972 [21] Appl. No.: 220,830

[57] ABSTRACT [30] Foreign Application Priority Data Feb. 3, 1971 Great Britain 3,823/71 This invention relates to a ladder capable of being erected from a plurality of similar rungs and links, the [52] US. Cl. 182/164, 182/46, 182/214, ladder being capable of being folded in a zig-zag man- 182/228 ner and also of being dismantled into a kit of compo- [51] Int. Cl. E06c 1/383 nent parts. The ladder comprises a plurality of rungs Field 0f Search and side links which in the extended form of the ladder 182/198, 46, 228 are adapted to maintain the spacing of the rungs and means between the rungs and the side'links for inter- [56] References Cited engagement.

UNITED STATES PATENTS 8/1952 Williams 182/198 8 Claims, 10 Drawing Figures PATENTEB SEN 1 I975 SHEET 1 OF 4 F IG] M @HUQM U@UOU SHEET 3 0F 4 PATENTED SEPH I973 PATENTED SEP] 1 I973 SHEET 4 0F 4 LADDERS The present invention relates to the provision of ladders, and has particular reference to foldable or collapsible ladders for the provision of access to the upper parts of masts or like upstanding elongate members.

In sailing boats and yachts, for example, the problem is frequently encountered in which running rigging fouls in such a way that they can only be freed at the mast head. Access to the mast head is usually by way of ratlines between the shrouds supporting the mast, which ratlines decrease in length towards the mast head due to convergence of the shrouds. In bad weather, it is often dangerous, if not impossible, to climb the ratlines to the mast head. Various types of ladders to ease access to the mast head have been proposed, but these, hitherto, have been of a permanent nature. There is a considerable need, therefore, on board small boats and yachts to provide a collapsible or foldable ladder, which may be employed to provide easier and safer access to the upper parts of the mast, than that presently afforded by ratlines. It will be appreciated that such ladders would also have general utility in the construction of building, the scaling of scaffolding, painting of flag-poles and the like.

According to the present invention, there is provided a collapsible or foldable ladder comprising one or more spacing elements which, in the extended state of the ladder can project laterally of the rungs, which elements have a concave outer face for. abutting the peripheral surface against which the ladder is to be employed, the arrangement being such that the ladder can be disposed with the rungs spaced from the said surface by the said spacing elements.

The present invention also includes a ladder comprising a plurality of rungs, and a'plurality of side links adapted to engage with said rungs, whereby the rungs are adapted to be spaced by side links extending therebetween, spaced engaging means on each rung, each of which is adapted to engage with at least two side links, and retaining means provided on each side link, adapted to engage with and retain each of a pair of spaced rungs, whereby the ladder is capable of being constructed from and dismantled into a plurality of similar rungs and similar links.

The engaging means of each rung may'permit relative rotation of the rung with at least one of said links associated therewith, whereby the ladder may collapse from an extended configuration to a folded configura: tion. Each rung is preferably rotatable with respect to each link. The engaging means may be a peripheral groove provided at or towards an end of each rung, adapted to co-operate with the slot in said link. Each rung may be substantially cylindrical, and the groove provided at the end thereof may be an annular groove in a cylindrical surface of the rung. The groove may have a radial projection at a part of its axial width, said projection being adapted to engage said slot to obtain relative rotation between said rung and said link.

The retaining means may comprise an elongate slot, adapted to accommodate said engaging means, said slot including a constriction dividing said slot into first and second portions, whereby on entering said engaging means into said first portion, pressure can be applied to said rung to snap said engaging means passed a constriction and into said second portion, whereupon said engaging means is retained in said second portion of the slot. The engaging means may be a cylindrical shank of reduced section with respect to the remainder of the rung, and the outer extremity of the rung may be defined by an outer disc portion having a generally radial projection. The first portion of the said slot may be an opening defined by the major segment of a circle of diameter such that the disc portion of the rung can pass therethrough. The second portion of the slot may be an opening defined by a major segment of a circle of diameter such that said shank can be rotatably accommodated therein. The constriction may be defined by the junction of the first and second segment portions.

The rungs and links are preferably formed of a plastics material, such as Nylon A100, whereupon the constriction can permit limited deformation to allow passage of the rung shank from the first slot portion to the second slot portion.

Where the rung shank or groove has a radial projection, the projection may be adapted to engage said constricted portion, thereby to restrain relative rotation between said rung and said link, in which circumstances, the central portion of the rung may be of substantially rectangular cross-section, to provide a flat tread thereon.

The invention further includes a ladder incorporating one or more spacing elements adapted to project laterally of the links constituting the ladder in the extended configuration to space said links and rungs from the surface against which the ladder is to be used. The spacing element may have an outer surface contoured to abut the surface against which the ladder is to be used, and the upper surface of the spacing element may be concave. The spacing element preferably has a pair of spaced arms, each of which is bifurcated at its end, and adapted to embrace a rung. One of each pair of bifurcations may be provided with a laterally extending lug, adapted to engage the retaining means in a link and to maintain said element at a substantially constant disposition with respectto said link. In an alternative embodiment of the invention, each bifurcation may have at its outer extremity, a laterally extending finger adapted to engage an edge of a contiguous link, whereby the said ladder and elements can be collapsed from an extended configuration to a folded configuration, each link being rotatable about the engaging means, relative to said element to subtend an angle therewith of not more than The links of the ladder may be rigid in the sense that they will not bend in the direction in which the spacing elements extend to engage the surface within which the ladder is to be used. The invention also includes an assembly of rungs and links capable of being erected to form a ladder in accordance with the present invention.

Following is a description by way of example only and With reference to the accompanying drawings of methods of carrying the invention into effect.

In the drawings FIG. 1 is a side view of a partially extended ladder in accordance with the present invention;

FIG. 2 is an end view of FIG. 1;

FIG. 3 is a detailed view partially sectioned of .the ladder of FIG. 1;

FIG. 4 is an end view of two ladders shown in FIG. 2, united to form a boarding ladder;

FIG. 5 is a detail of FIG. 4; FIG. 6 is a plan view of a spacer for the ladder of FIG. 1;

HQ. 7 is a Section on 7 7 of FIG. 6;

FlG. 8 is a side view of the spacer of FIG. 6;

FIG. 9 is a perspective of an alternative spacer in accordance with the present invention;

FlG. 10 is a perspective of another embodiment of a rung for use in the ladder of the present invention.

The ladder of FIG. 1 is composed of a plurality of links 10 and rung members 20 each of which are adapted to be joined together from a kit of similar links and rungs to form a foldable ladder having a plurality of spaced parallel rungs 20; the spacing of adjacent rungs being defined and maintained by links 10. The links and rungs are formed of a plastics material and preferably from a material such as Nylon A 100 or glass fibre reinforced nylon.

Each link 10 is an elongate piece of plastic having rounded ends 11. Each link is provided towards each end with a rung slot 12 comprising a first portion 13 defined by the major arc of a segment of a circle, and a second portion 14 defined by the major arc of a segment of a circle of diameter smaller than said first circle, the arrangement being such that the point of junction between the arcs of the circles defining said first and second slot portions terminate in an inwardly directed portion 15 constituting a constriction within the slot. Each link 10 is provided with a central slot 16 defined by first circle portion 17 which extends into a longitudinal slot 18 via an intermediate portion 19, defined by a circle of diameter substantially smaller than that of circular portion 17, the arrangement being such that principle slot portion 17 of central slot 16 and intermediate slot portion 19 are each defined by the major arc of a segment of a circle such that the point of juncture between said arcs at 19 defines a constriction in the manner described above with regard to the rung slots 12.

Each link 10 is further provided with a longitudinal slot 21 for the purpose of economising on the use of material employed in the manufacture of the link.

Each rung is constituted by a cylindrical rod provided with a peripheral groove 22 towards each end thereof each groove being of axial width sufficient to accommodate the thickness of two of links 10. The end portion 23 of each rung 20 is provided with a radially disposed lug 24.

ln use, the ladder is constructed from a kit of parts comprising a plurality of rungs 20 and a plurality of links 10. The end portion 23 of each rung 20 is entered into the first portion 13 of slot 12 with the lug 24 extending throughconstriction 15 into the second slot portion 14. When the extended portion 23 has been passed through the slot 12, the shank defined by groove 22 is freely rotatable within the first portion. The application of pressure to the rung axially of the link in a direction towards the adjacent rounded end urges said shank through the constriction, into the second slot portion 14 the diameter of the circle defining said second slot portion 14 being selected to receive said shank for rotation therein. The link 10 is then moved until the inner side face thereof is juxtaposed the shoulder defined by the cylindrical portion of rung 20 defining the inner extremity of groove 22. A second link is then entered over the end portion 23 of the rung 20 in a similar manner to the first link, and the two links are then rotated about the shank of groove 22 until they are disposed at substantially 180 to each other. A similar construction is arranged at the other end of rung 20. A

second rung is then engaged with an inner link in the manner described above, and the end 23 of said second rung is then entered into the opposite end of said second link to form the next rung in the ladder sequence. Continued assembly of the components in the manner described above results in the production of the foldable ladder.

The ladder can be extended from a zig-zag folded configuration as shown in FIG. 1 to an extended position.

Two similar ladders 50 and 50 can be joined side by side with any other number of ladders to form a board ing ladder. The jointing is made upon alternate links by means of a jointing member 25. Jointing member 25 comprises a central cylindrical portion 26 having a radially disposed flange 27. The cylindrical portion 26 of flange 27 are terminated at each end by means of an end piece 28 in the form of a disc eccentrically disposed with respect to cylindrical portion 26 and arranged to cover the ends of flange 27 and portion 26. In use, the disc shaped end piece 28 of member 25 is entered into the central opening 17 until the cylindrical portion 26 and flange portion 27 is disposed therein. The member 25 is then rotated until the flange 27 is juxtaposed elongate slot 18 and movement of the memher to enter flange 27 into slot 18 causes cylindrical portion 26 to be snapped passed constriction 19' into intermediate cylindrical portion 19. A similar course of action for the next adjacent link on the adjacent ladder permits two ladders to be united in the manner of a boarding ladder.

The ladder may include a plurality of spacers 30 each defined by a pair of spaced arms 31 and a laterally extending rib 32 uniting arms 31. Each of arms 31 is bifurcated at its forwarded end to provide a pair of bifurcations 33 adapted to embrace the cylindrical portion of rung 20. Each of the arms 31 extends rearwardly of rib 32 to terminate in rope engaging fingers 34. A rope engaging slot 35 is also juxtaposed fingers 34. One'of each pair of bifurcations 33 carries an outwardly extending lug 36.

In use, the bight defined by bifurcations 33 is entered over the cylindrical rung and the lugs 36 are entered into the first portion 13 of rung slot 12 at the link 10 adjacent arm 31, the arrangement being such that the lug engages with the first portion 13 of rung slot 12 to maintain spacer 30 at a substantially constant disposition with respect to said link, the arrangement being such that with the ladder in the extended position, the spacer 30 serves to abut a surface against which the ladder is to be employed. Where the ladder is to be employed in conjunction with the mast of a yacht or a similar elongate pole, then the rib 32 is provided with a concave rear surface adapted to accommodate and engage with. the pole or mast, in which case short lengths of rope may be passed from the rope holes provided about the mast or pole to engage the rope guides and rope receiving orifice in the rearward extension of the other arm.

An alternative embodiment of spacer 30 is shown in FIG. 9. This comprises a pair of spaced forwardly extending arms 40 each of which is bifurcated at its forward end to form bifurcations 41. Each of bifurcations 41 carries a laterally extending finger 42, the arrangement being such that in use, the spacer 30 being made of a plastics material, the arms 40 can be biassed inwardly and the bifurcations 41 are entered to embrace a rung 20 so the fingers 42 extend ouwardly of and abut the edges of the two links adjacent thereto remote from rib 32. In this configuration, the links are free to rotate about the rung until a longitudinal edge thereof abuts fingers 42.

An alternative embodiment of the rung in accordance with the present invention is illustrated in FIG. 10. The cylindrical portion 20 is provided with a central portion 60 of substantially rectangular configuration which is provided with a tread 61. The end portion 23 of rung 20 is provided with a radial projection 62 which extends inwardly of the inner face of end portion 23 also to extend radially from the shank portion of the rung defined by groove 22, the projection 62 extending inwardly to the extent of the width of one link 10, the arrangement being such that on entry of the end portion 23 to rung slot 12 of a pair of links 10 the snapping of the reduced portion or shank defining groove 22 in rung 20 into the second slot portion 14 can be effected by disposing the projection 62 into the constriction so that in the retained position, the projection extends into the first portion to prevent rotation of the rung with respect to the outer link, the inner link being free to rotate with respect to said outer link and said rung.

The ladder described above may be used in a number of different ways. The free ends of the links 10 secured to the uppermost rung may be drawn together by means of a rope and secured to the halyard of a mast, and the ladder may be hauled up the mast. Alternatively, a pair of hooks each having a rung slot, corresponding to that in each link 10 and being of the same width as link 10 may be snapped about the shank of the uppermost rung in place of the links normally secured thereto. The hooks may engage the ridge or pulpit of a surface to which the ladder is to be attached.

in a further embodiment, a bracket having a pair of spaced hooks adapted to receive the said shank portion of the uppermost rung may be secured to a surface for supporting the ladder.

What l'claim is:

1. A ladder comprising a plurality of rungs and a plurality of side links, said rungs and said side links'being constructed of a plastic material, each of said rungs having an engaging portion integrally formed at each end thereof to interconnect at least two consecutive side links, and each of said side links defining spaced retaining means at each end for snap engagement with the engaging portion of one of Said rungs whereby said rungs and said side links are selectively interengagable to form a ladder in which the rungs are maintained in parallel spaced relationship by said side links.

2. A ladder as claimed in claim 1 characterised in that the engaging portion on each rung is rotatably interconnected with at least one of said links associated therewith, whereby the ladder can be collapsed from an extended configuration to a folded configuration.

3. A ladder as claimed in claim 1 characterised in that the engaging portion is a peripheral groove provided at or towards an end of said rung.

4. A ladder as claimed in claim 3 characterised in that said groove has a radial projection over at least part of its width, said projection being adapted to engage said retaining means on said side link, to restrain relative rotation between the rung and said link.

5. A ladder as claimed in claim 1 characterised in that the retaining means comprises an elongate slot adapted to accommodate said engaging means, said slot including a constriction, dividing said slot into first and second portions whereby on entering said engaging means into said first portion pressure can be applied to said rung to snap said engaging means passed said constriction and into said second portion, whereupon said engaging means is retained in said second portion of the slot.

' 6. A ladder as claimed in claim 1 characterised by the inclusion of one or more spacing elements adapted to project laterally of the links of said ladder in the extended state to space said links and rungs for the surface against which the ladder is to be used.

7. A ladder as claimed in claim 6 characterised in that the spacing element has a pair of arms each of which is bifurcated at its end, and adapted to embrace a rung. v 8. Apparatus as claimed in claim 7, characterised in that each bifurcation has at its outer extremity a laterally extending finger adapted to engage the edge of a contiguous link, whereby said ladder and elements can be collapsed on an extended configuration and wherein each link is rotatable about the engaging means relative to said element to subtend an angle of not more than 

1. A ladder comprising a plurality of rungs and a plurality of side links, said rungs and said side links being constructed of a plastic material, each of said rungs having an engaging portion integrally formed at each end thereof to interconnect at least two consecutive side links, and each of said side links defining spaced retaining means at each end for snap engagement with the engaging portion of one of Said rungs whereby said rungs and said side links are selectively interengagable to form a ladder in which the rungs are maintained in parallel spaced relationship by said side links.
 2. A ladder as claimed in claim 1 characterised in that the engaging portion on each rung is rotatably interconnected with at least one of said links associated therewith, whereby the ladder can be collapsed from an extended configuration to a folded configuration.
 3. A ladder as claimed in claim 1 characterised in that the engaging portion is a peripheral groove provided at or towards an end of said rung.
 4. A ladder as claimed in claim 3 characterised in that said groove has a radial projection over at least part of its width, said projection being adapted to engage said retaining means on said side link, to restrain relative rotation between the rung and said link.
 5. A ladder as claimed in claim 1 characterised in that the retaining means comprises an elongate slot adapted to accommodate said engaging means, said slot including a constriction, dividing said slot into first and second portions whereby on entering said engaging means into said first portion pressure can be applied to said rung to snap said engaging means passed said constriction and into said second portion, whereupon said engaging means is retained in said second portion of the slot.
 6. A ladder as claimed in claim 1 characterised by the inclusion of one or more spacing elements adapted to project laterally of the links of said ladder in the extended state to space said links and rungs for the surface against which the ladder is to be used.
 7. A ladder as claimed in claim 6 characterised in that the spacing element has a pair of arms each of which is bifurcated at its end, and adapted to embrace a rung.
 8. Apparatus as claimed in claim 7, characterised in that each bifurcation has at its outer extremity a laterally extending finger adapted to engage the edge of a contiguous link, whereby said ladder and elements can be collapsed on an extended configuration and wherein each link is rotatable about the engaging means relative to said element to subtend an angle of not more than 90* 